This invention relates to a composite structure for electronic components comprising a growth substrate, an intermediate layer arranged on the growth substrate, and a diamond layer applied over the intermediate layer, and to a process for producing such a composite structure as disclosed in published European Patent Application No. EP 282,054 A1.
Published European Patent Application No. EP 282,054 A1 describes a composite structure for electronic components and a process for producing such composite structures. The composite structure comprises a growth substrate of crystalline Si (silicon) or of crystalline GaAs (gallium arsenide), on which an intermediate layer of crystalline SiC (silicon carbide) is deposited and a diamond layer deposited on the intermediate layer, in which the layers are deposited by means of CVD (chemical vapor deposition) on the growth substrate. The intermediate layer of SiC thereby serves to diminish (compensate for) the prevailing lattice mismatch of approximately 52% or approximately 58% between the growth substrate on the one hand, whose lattice constant is approximately 5.43 .ANG. (Si) or 5.65 .ANG. (GaAs), and the applied diamond layer on the other hand with a lattice constant of approximately 3.57 .ANG., with respect to the lattice constant of the diamond layer, in order to thereby facilitate an acceptable growth of the diamond layer on such growth substrates. Since SiC has a lattice constant of approximately 4.36 .ANG., its lattice mismatch with respect to the lattice constant of the growth substrate amounts to approximately 25% (Si) or 30% (GaAs), and with respect to the diamond layer 22%, in which case the difference is with respect to the lattice constant of the diamond layer. By means of the bridging of the crystalline SiC-layer, the effects of the existing lattice mismatch on the quality of the deposited diamond layer are minimized. Despite this measure, the quality of the deposited diamond layer, however, is still unsatisfactory because the number and density of the grain boundaries and displacements is very high.